Abstract

Charles Darwin was born 200 years ago this year and his monumental work On the origin of species, laying the foundation of modern evolutionary theory driven by natural selection, was published 150 years ago. Earlier in 1759, The Royal Botanic Gardens, Kew, were established. This year's special issue of Bradleya celebrates these anniversaries with the principal theme of evolution of succulents. Bradleya 27 includes the following articles:

•Editorial: Darwin and Kew anniversaries by Colin Walker
•Charles Darwin's succulent plants by Gordon D Rowley
•Living under temporarily arid conditions - succulence as an adaptive strategy by Urs Eggli and Reto Nyfeller
•Evolution of cacti driven by genetic drift not selection bt Root Gorelick
•Evolution of characters in the Opuntioideae by M Patrick Griffith
•Insect flower visitors and pollinators of cacti from the southwest USA by Zlatko Janeba
•On the evolution of nectaries in the Aizoaceae by H.E.K Hatrmann and I.M.Niesler
•Kew and its collections of succulent plants by David Hunt and Nigel Taylor
•The composite structure of cactus spines by Urs Schlegel
•Stapelia hirsuta L. and early portrait by H.A.Jonkers
•Rectification of a mistake by G.W.Reynolds on a Malagasy Aloe (Asphodelaceae) and description of a new species by Jean-Bernard Castillon
•The identity of Sansevieria arborescens (Ruscaceae), with an amplified description and description of a new species by Leonard E.Newton
•Priority of Aloe teissieri over Aloe andohahelensis by Susan Carter and John Lavranos
•Ceropegia thailandica (Asclepiadoideae-Ceropegieae), a spectacular new Thai species by Ulrich Meve
•Aloe arborescens Miller (Asphodelaceae) is spreading in Portugal by Gideon F.Smith and Estrela Figueiredo